This invention relates generally to eye surgery and more particularly to fiber optic handpieces used for laser eye surgery.
The treatment of glaucoma and its symptoms has resulted in a wide variety of approaches. Surgical treatment methods include the use of cryotherapy, ultrasound, microwave heating, microsurgery and a number of laser wavelengths and target structures. Much recent laser glaucoma treatment has concentrated on techniques to reduce aqueous production and intraocular pressure by selective destruction of the ciliary body and related processes. The ciliary processes include the ciliary muscle and the blood vessels within the ciliary body. The term ciliary body is hereinafter to be understood to refer to the ciliary body as a whole and its related processes. Infrared lasers, predominantly Nd:YAG lasers operating at 1.06 .mu.m, have been used to deliver laser energy of a few joules per treatment site. Laser delivery for such cyclophotocoagulation has been accomplished both by free beams directed through air to a patient seated at a special slit lamp and by fiber optic handpieces placed in contact with the patient's eyeball. Handpieces have been used both with and without beamshaping contact tips.
These techniques have advantages as well as drawbacks to their widespread clinical use. Delivery of a freely propagating laser beam to a patient seated at a slit lamp has higher clinical safety margins than with other techniques. This is notable, since thermal damage to the lens has been commonly encountered by researchers applying laser energy in the region of the ciliary body. Drawbacks to the slit lamp technique are several. Since the ciliary body targets are not visible to the doctor during the procedure, aiming of the laser is by visual estimation, which contributes to variation in result from patient to patient and from doctor to doctor. Also, clinical efficiency of free beam delivery through air is less than that of contact methods, as tissue coupling efficiency is reduced by 10-50%.
Current contact handpieces deliver laser energy via a fiber optic, usually held by the surgeon normal to the surface of the eyeball at a point immediately above the ciliary body. Laser access to the ciliary body is good, but inadvertent thermal damage to the crystalline lens is an undesirable side effect typical to this method. The laser contact method is more efficient than the noncontact method, however, accomplishing similar results with less laser energy, thus affording the possibility of using more compact laser sources. Additionally, direct placement of the laser handpiece against the eyeball makes positioning easier and more consistent than with a slit lamp.